1. Field of the Invention
The present invention relates to a tube-socket assembly and a method of manufacturing the same, and more particularly, to a tube-socket assembly and a method of manufacturing the same that can provide a secure fastening structure by reinforcing seal between a tube and a socket.
2. Description of the Related Art
A research and development of a tube-socket direct fastening structure, i.e., a tube-socket assembly that directly fastens a tube and a socket has been performed. Particularly, when connecting tubes in which a high pressure fluid flows, secure seal that can minimize leakage of a connection portion thereof is requested.
FIGS. 1 and 2 illustrate conventional tube-socket assemblies. The tube-socket assembly of FIG. 1 has a fastening structure by so-called caulking.
Referring to FIG. 1, after an inner bead 11 is formed, a tube 10 is inserted into a socket 20, and by compressing a portion of the socket 20 using a punch, the portion of the socket 20 caulks the inner bead 11 and seal is thus formed.
In the tube-socket assembly using caulking of FIG. 1, seal is generally formed along an entire outer circumferential surface of the inner bead 11. Accordingly, a portion in which seal is formed is distributed over a wide area, when an area in which seal is formed increases, a fastening force between the socket 20 and the tube 10 is deteriorated, and thus leakage through a fastening portion increases. Even if a pressure applied by a punch for caulking increases, an area of a portion in which seal is formed does not change, and thus deterioration of a fastening force due to pressure increase by a punch cannot be solved.
Further, when a pressure applied by a punch increases, at a position 12 corresponding to a caulking forming portion enclosing the inner bead 11, an inner diameter of the tube may decrease, compared with other portions. That is, as a pressure applied by a punch increases, a phenomenon that materials forming the tube 10 are formed in a lump occurs in a portion in which deformation occurs within the tube 10 and thus a phenomenon that the tube 10 becomes narrow at a position 12 of FIG. 1 occurs.
FIG. 2 illustrates another example of a conventional tube-socket assembly. In the tube-socket assembly of FIG. 2, after inserting a tube 30 in which an outer bead 32 is formed into a socket 40, by applying a pressure to a tube portion positioned within the socket 40 using a punch, an inner bead 31 is formed and seal is formed between the inner bead 31 and the socket 40. A fastening form between the inner bead 31 and the socket 40 is referred to as a beadlock.
In a tube-socket assembly of a beadlock form, in a process of forming the inner bead 31 after positioning the socket 40 at a predetermined position, at an initial stage of forming the inner bead 31, as an outer circumferential surface of the inner bead 31 and a vertical end portion 41 of a penetration opening of the socket 40 line-contact, an area of a portion in which seal is formed may be minimized. However, in a tube-socket assembly of a beadlock form of FIG. 2, in order to form the inner bead 31 of an enough large height, as a pressure applied by a punch increases, a contact area of the outer circumferential surface of the inner bead 31 and the vertical end portion 41 of the penetration opening of the socket 40 increases, and thus seal may decrease.
FIGS. 3A to 3C illustrate a process of forming the conventional beadlock form tube-socket assembly of FIG. 2.
Referring to FIGS. 3A to 3C, a conventional beadlock form tube-socket assembly forming process starts from a process of forming the outer bead 32 in the tube 30. Thereafter, at a position where the outer bead 32 contacts with an outer end portion of the socket 40, the socket 40 is positioned. After disposing the socket 40 on the tube 30, by compressing a portion of the tube 30 toward the socket 40 using a punch, the inner bead 31 is formed. In this way, after forming the outer bead 32 and installing the socket 40, as the inner bead 31 is formed, in a compression process using a punch, the socket 40 may be pushed toward the outer bead 32. Accordingly, seal between the inner bead 31 and the socket 40 may be deteriorated.
As in the structure of FIG. 1, in the beadlock form tube-socket assembly of FIG. 2, in a process of forming the inner bead 31, as a compressing force is applied, a phenomenon that materials forming a tube are formed in a lump about a portion in which deformation occurs within the tube 30 occurs, and thus a phenomenon that the tube 30 become narrow occurs at a position 33 of FIG. 2.
Further, in a state where the outer bead 32 is formed, when an excessive pressure for forming the inner bead 31 is applied to the tube 30, a coating layer formed in a surface of the outer bead 32 may be peeled off, and in this way, when coating of a portion of the outer bead 32 exposed from the outside of the socket 40 is damaged, corrosion resistance of the tube 30 may be deteriorated.